Jun 26, 2018 - 12:58 PM
Lake Brienz ferry trip is covered in Swiss pass but you must find out about the First from its respective website, or from Swiss travel website.
As far as covering both of them is concerned, it depends on you how much time you want to spend on the Grindelwald summit. From website you will know that it has various adventure activities for all ages and levels.
The Brienz lake is also beautiful and assuming you board ferry from Interlaken and full round trip will be 3-4 hours from interlaken-Brienz-interlaken.
my advice is take the Brienz ferry to Brienz and do Brienz rothorn. It’s also a beautiful summit and a 100 years old steam engine is used for going to summit. Check out their website.